In this research, we chose the exact inhibitor [(S)-N-(2-(2-cyano-4,4-difluoropyrrolidin-1-yl)-2-oxoethyl)-6-(methoxy) quinoline-4-carboxamide, IC50 = 8.5 ± 0.9 nM (3)] of FAP, and its analogue (S)-N-(2-(2-cyanopyrrolidin-1-yl)-2-oxoethyl)-6-(methoxy) quinoline-4-carboxamide as the standard compounds, labeled them with the PET radionuclide 11C (half-life, 20.4 min), and examined the potential of the tracers as PET molecular imaging probes in tumor model mice. This evidence concerns the gene FAP and neoplasm.